3,439 research outputs found

    Electrodynamics of Black Holes in STU Supergravity

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    External magnetic fields can probe the composite structure of black holes in string theory. With this motivation we study magnetised four-charge black holes in the STU model, a consistent truncation of maximally supersymmetric supergravity with four types of electromagnetic fields. We employ solution generating techniques to obtain Melvin backgrounds, and black holes in these backgrounds. For an initially electrically charged static black hole immersed in magnetic fields, we calculate the resultant angular momenta and analyse their global structure. Examples are given for which the ergoregion does not extend to infinity. We calculate magnetic moments and gyromagnetic ratios via Larmor's formula. Our results are consistent with earlier special cases. A scaling limit and associated subtracted geometry in a single surviving magnetic field is shown to lift to AdS3×S2AdS_3\times S^2. Magnetizing magnetically charged black holes give static solutions with conical singularities representing strings or struts holding the black holes against magnetic forces. In some cases it is possible to balance these magnetic forces.Comment: 31 page

    A single-phase synchronization technique for grid-connected energy storage system under faulty grid conditions

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    The control of a single-phase grid-connected energy storage system (ESS) requires a very fast and accurate estimation of grid voltage frequency and phase angle. A phase-locked loop (PLL) based synchronization algorithm usually extracts this information. The operation and control of the entire system are directly affected by the performance of PLL. In this article, a novel advanced single-phase PLL (ASÏ•PLL) technique with reduced complexity is proposed for the fast and accurate extraction of grid information in an ESS under distorted and abnormal grid conditions, including harmonics, interharmonics, dc offset, and grid faults. The proposed method provides a faster dynamic response, lower frequency overshoot, and accurate estimation under off-nominal grid frequencies with reduced computational complexity in comparison with the existing method. The advanced performance of the proposed ASÏ•PLL is verified through the simulation and experimental results

    Online reduced complexity parameter estimation technique for equivalent circuit model of lithium-ion battery

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    For control-oriented battery management applications in electric vehicles, Equivalent Circuit Model (ECM) of battery packs offer acceptable modelling accuracy and simple mathematical equations for including the cell parameters. However, in real-time applications, circuit parameters continuously changes by varying operating conditions and state of the battery and thus, require an online parameter estimator. The estimator must update the battery parameters with less computational complexity suitable for real-time processing. This paper presents a novel Online Reduced Complexity (ORC) technique for the online parameter estimation of the ECM. The proposed technique provides significantly less complexity (hence estimation time) compared to the existing technique, but without compromising the accuracy. We use Trust Region Optimization (TRO) based Least Square (LS) method as an updating algorithm in the proposed technique and validate our results experimentally using Nissan Leaf (pouch) cells and with the help of standard vehicular testing cycles, i.e. the Dynamic Driving Cycle (DDC), and the New European Driving Cycle (NEDC)

    Modeling and Experimental Investigation of Energy Management for Hybrid Electric Vehicle based on Variable Structure Control Strategy

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    The current study presents real-time modeling and non-linear controllers-based energy management system (EMS) for multi-energy hybrid Electric Vehicle (EV), where a detailed physics-based dynamic vehicle model has been considered. The main objective of the paper is to regulate the power flow, stabilize DC voltage for an EV driven by a brushless DC motor, and ensure effective power sharing in a hybrid electric system under complex driving circumstances. The approach is based on tracking the reference battery current by backstepping sliding mode control for optimal power distribution. Subsequently, Integral Sliding Mode Control based on barrier function (NBS-ISMC), and Fractional Order Terminal Sliding Mode Control (FOTSMC) are implemented to control the switching operation of converters for Photovoltaic (PV) and Ultra-capacitor (UC), respectively. User-defined and practical standard drive cycles are selected to test the effectiveness of proposed reference current controllers

    Risk Factors of Diarrhoea in Malnourished Children Under Age of 5 Years

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    Background: Acute infectious enteritis remains one of the commonest causes of death among infants and children in developing countries. Acute enteritis is defined as a loss of stool consistency with pasty or liquid stools, and/or an increase in stool frequency to more than three stools in 24 hours with or without fever or vomiting. Human survival depends on the secretion and reabsorption of fluid and electrolytes in the intestinal tract. The objective of the study is to evaluate the risk factors of diarrhoea in children under age of 5 years. Methodology: It was an observational study. Study was completed in about six months. Non-probability purposive sampling technique was used. In this study, 270 samples were taken from Diarrheal ward of The Children Hospital Lahore, Pakistan. Results: In this study, out of 270 patients, 58.52% were males and 41.48% were females. 90.37% patients were vaccinated. 54.81% had weaning history. 91.85% patients had feeding history. 29.26% had blood in stool. 96.67% patients were dehydrated. 95.56% patients had loose watery diarrhoea. 62.96% patients used boiled water. 58.52% patients consumed less than half litre of water, 30.00% patients consumed 1 litre of water and 11.48% patients consumed > 1 litre of water. 49.18% patients had proper hygiene. 38.15% mothers of patients were well educated. 40.37% patients had model household condition. 57.41% patients lived in rural area and 42.59% patients lived in urban area. Conclusion: The variation in the level of diarrheal morbidity was well explained by maternal education, income, personal hygiene, refuse disposal system and the effect of health extension programme

    Inter-strain cross-fertility tests on cultures from Israel and America in the homothallic fungus, Sordaria fimicola

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    Inter-strain cross-fertility was studied in relation to geographical origin in a homothallic, self-fertile fungus, by looking for hybrid perithecia in wild-type x ascospore colour mutant crosses. Strains from opposite slopes in \u27Evolution Canyon\u27, Israel, showed no cross-fertility with American or Canadian strains; there was excellent cross-fertility with other strains from the same slope, but an occasional lack of cross-fertility with strains from the other slope
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